Here's a nice way to recover notes from your iPhone without having to mail them to yourself--although it's not for the faint of heart. James Duncan Davidson located where iTunes stores its iPhone backup data--at least mostly. There's an error in his write-up. It's actually stored in your home folder's application support directory in MobileSync/Backup. For me, that works out to be /Users/ericasadun/Library/Application Support/MobileSync/Backup. But getting back to Duncan Davidson's story, he took a peek at those files and noticed they were some sort of compressed SQLite3 files.
Following on that, "Mr. Flip", who is one of the iPhone web developer Google group members posted this simple extraction utility written in Perl. When run, it converts each of the backup files to a normal well-named SQLite3 db file. Following Flip's directions, I then downloaded a copy of the OS X version of SQLite Browser from Sourceforge and used it to view the contents of the backup db files.
Interestingly enough, when viewing the db files directly from the command line (via sqlite3 notes_01.db and .dump) I discovered that the iPhone saved my entire history of edits for my note files as well as the actual final content.